Field of the Invention
The present disclosure relates to a lubrication device of a high pressure pump for a common rail system, and more particularly, to a lubrication device of a high pressure pump for a common rail system, enabling to improve lubrication performance of a friction portion where a roller and a shoe is in contact with each other.
Description of Related Art
Generally, a high pressure pump 10 used in a common rail system includes a pump housing 11, a roller 12, a shoe 13 and a plunger 14, as shown in FIGS. 1 and 2. In the pump housing 11, a shaft chamber 11a, a roller chamber 11b and a spring chamber 11c are formed to be connected each other.
A cam shaft 21 provided with a cam 21a is arranged rotatably in the shaft chamber 11a, the roller 12 and the shoe 13 are arranged to contact the cam 21a in the roller chamber 11b, and a spring 16 is arranged through a spring seat 15 in the spring chamber 11c. 
One end of the plunger 14 is arranged to be in contact with the shoe 13 and the other end of the plunger 14 is arranged to be disposed on a fuel compression chamber 17 placed between an inlet valve 22 and an outlet valve 23.
The inlet valve 22 is arranged through a fuel channel connected to a low pressure pump 24 and the outlet valve 23 is arranged through a fuel channel connected to a common rail 25.
Accordingly, when the cam shaft 21 rotates by the driving of an engine, the roller 12 rotates in accordance with lift of a cam profile to push the shoe 13 such that the plunger 14 reciprocates with the shoe 13 being pushed wherein fuel at a low pressure, which is supplied to the fuel compression chamber 17 through the inlet valve 22 by the movement of the plunger 14, is compressed and flowed out to the common rail 25 through the outlet valve 23.
Meanwhile, the roller 12 and the shoe 13 are arranged to be in contact each other with strong pressure wherein when a friction portion M1 is not lubricated sufficiently, where the roller 12 and the shoe 13 contact each other, it is to be worn seriously with friction, and be sand-burnt in severe cases. In general, the friction portion M1 of the roller 12 and the shoe 13 is lubricated using fuel of a low pressure pump 24 to prevent the wearing and sand-burning.
That is, according to a related art, the friction portion M1 of the roller 12 and the shoe 13 is lubricated using a first lubrication channel 31 connecting the low pressure pump 24 and the shaft chamber 11a of the pump housing 11, and a second lubrication channel 32 connecting the shaft chamber 11a and the spring chamber 11c wherein the fuel of the low pressure pump 24 fills in the shaft chamber 11a and then in the spring chamber 11c, and also the friction portion M1 of the roller 12 and the shoe 13 is applied with the fuel to be lubricated.
However, according to the related art as configured above, a channel through which lubrication fuel moves to the friction portion M1 of the roller 12 and the shoe 13 is long and thus the cam shaft 21 drives before lubricating sufficiently the friction portion M1 of the roller 12 and the shoe 13. In this case, the friction portion M1 of the roller 12 and the shoe 13, to which strong compression load applies, is to be worn seriously and further sand-burnt due to friction, thereby causing a poor high pressure pump 10.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.